/Engine/Source/Runtime/Core/Public/Templates/SharedPointer.h
Assignment to a nullptr pointer. The object currently referenced by this shared pointer will no longer be referenced and will be deleted if there are no other referencers.
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr) & operator= ( [SharedPointerInternals::FNullTag](API\Runtime\Core\Templates\FNullTag) * )